[Feature Request] Cache + Update FAQ/Readme

[UpscaleAnon]

Hey, nice program. I was wondering if there will ever be a sort of cache system implemented?
Since I download stuff, then optimize it losslessly through Pinga to save space, then move to a different folder, but your program only checks if file already exists in a location, not whether it has been previously downloaded, so it would just re-download.
I've been using this: https://github.com/FurryBotCo/E621Downloader for a while now, but it is insanely slow (especially over time), can only do 1 tag at a time (and since I'm downloading thousands of different artists, that's gonna be a pain in the ass), but it has a cache that checks if I've downloaded something before, even if I move the files.
It would be really nice if your program got a similar cache, or at least have it scan in a different directory than what it's downloading to, though a cache would probably benefit more people.

I noticed in the config.json there is ""fileNamingConvention": "md5""
And I found out that I can set it to ID instead of md5 and it'll save as the post ID which is nice. I think this should probably be mentioned in either the readme or the FAQ . But the main page of this github project seems a bit out of date, as the windows install tells you to get GCC or MSVC, even though you can just download latest release and run as is without doing any of that.
There's also no mention of what "safemode" does or whether or not I should use it

Thanks a lot either way for making such an amazing program.